American guns aren't valued like Brit guns so all numbers are skewed.

American guns have value because of originality and rarity. Brit guns have value because of current replacement cost and restored condition. (A general oversimplification)

A fully restored to as-new westley Richards boxlock may fetch $6000-$7000. A fully restored Parker VH may fetch $1700. I know, I've had and sold both. Both are of the same level of engraving and overall quality. (I much prefer the westley)

It all goes back to the differences in how American guns are valued.